Signaling system



Patented Aug. i9, 119245:.

unire 'res J'GHN TOO'MEY, F NEW YO'RK, N. Y., ASSIGNOR yTO AM'ERCAN TELEEHQNE AND TELEGRAPH COMPANY, A C()RPORliTllQlil 0F NEW YORK.

srcivanrne sYsfrnr-li'.

Application iiled Becember, i920; Serial No. 432,822.

To all whom t may conce/m Be it known that l, JOHN F. Tooiunr, residing at N ew York, iii the county of New York and State of New York, have invented certain Improvements in Signaling Systems, of which the following is a specification.

This invention relates to. signaling systems and especially to an arrangement for controlling the transmission over a line cir` cuit of relatively high frequency currents designed to operate the signaling apparatus connected with the said line circuit.l

lt has been ciiistoinary, heretofore in operating the signaling apparatus connected with a telephone circuit, to use an alternating current of relatively low frequency. Signaling current of 16 cycle or other frequencies of the saine order of magnitude were used, and is still used upon telephonel circuits having no telegraph equipment associated therewith. When circuits began to be used for joint telephone and telegraph transmission, it was necessary to raise the frequency of the signaling current to 133 cycles so as to prevent interference with the telegraph equipment. Such frequency proved satisfactory until the development of the carrier systems, on which the ,sig naling impulses are impressed upon a carrier wave. lWith such development it has beeny found desirable to further increase the frequency of the signaling current, so as to take it out of the range of relatively low frequencies which are used for the carrier telegraph channels, and at the saine time to keep said signaling frequency within the range of voice frequencies.

It is the object of this invention to provide an arrangement for controlling` the application of signalingl current of relatively high frequency to a line circuit.

This invention will be better understood from the following description wheny read in connection with the attached drawing showing one form of embodiment of the in vention. i

In the drawing L, represents aline circuit extending to a distant office and having con nected therewith terminal apparatus preferably similar to that shown in the figure. The line circuit L, terminates at the switchboard in a jack il, which is adapted to cooperate with a plug l?, of a cord circuit which may be of any well-known type. Bridged acrossthe line circuit L, is ringdown relay El which is responsive to the application of ,i lowy frequency ringing cui rent when relay ftzis operated. Associated with the relay filare the relays R3 and lig, Rabeing adapted to light the line signal l andR4 being'adapted to open the circuit of the relay R1 when the plug P1 of a cord circuit is inserted "in the jack J1. The relay R5 responsiveto the applicationl of low fie quency ringing rcurrent from the cord circuit associated with the plug P, is designed to effect the operation let relays R6 and which serve to connect a source of relatively high frequency current to the line L, and also serveto start in operation the apparatus by means of which the period of application of the high frequency current may be controlled. Relay RS serves to prevent the'coutinued application of the high frequencyl ringing current to the line in case an operator maintained a ringing key of her coralL circuit in its operative position for a longer period of time than that during which the apparatus was designed to transmit a sig nal. An interrupter 2 cooperates with the stepping magnet 3 for controllng the opH eration of the `rotarytype switches S1, S2, S3 and S4., Relay l, is designed to control the disconnection of the high frequency ringing current y when the sending switch S, reaches a pre-determined point in the course of its rotation. `Relays R10, Ril, R12 and Rl, operate when highfrequency ringing current is received over the line from a distant station and they in turn effect the operation of relaysltq,l and R2 for yproducing a signal at the switchboard associated with jack Jl,

Relay R15 and the' switches S, and are designed to cause the wipers of the rotary switches S1 and S2 to return to their normal positions after the transmission or reception of signaling .current over the said line. Bridged across the line L, at the points a,

i 4 is an input circuit 5 which is adapted to of the various parts ofthe arrangement in which this invention is embodied, the invention will be clearly understood from the Cil `cated by the arrows.

following description of its mode of op-v eration.

Let it be assumed that the operator at A desires to signal to the operator at the distant end of the line L1. To do this, the

said operator lwill depress the key K1 there- 9 and capacitv 10 the circuit of the relay R5 offers a low impedance path for 20 cycle current but a high impedance path for high frequency current of approximately 2000 cycles that may be transmitted from the distant station over the line L1. lll/hen relay operates, relays ART and R6 are likewise operated by current flowing from battery B1, windings of relays R7y and RJ., in series, through contact 11 of relay R8 and over conductor 12 and through contact of relay to ground. By the operation of relay R6 lits armatures with which the line L1 is connected are brought into contact with a circuit connected with a source of, for example, 2000 cycle ringing current. This results accordingly in impressing upon the line L,L a relatively high frequency ringing current which is adapted to operate in a manner which will be made clearer later, the signaling apparatus connected with the distant end of the line L1. Through the operation of the relay R, its contacts 13 and 14 are closed. By the closing of con'- tacts 13 relays R6 and R7 are locked up over contact 15 of relay R9. By the'closing of contact 14 the interrupter 2 is connected with the stepping magnet 3 and thev battery associated therewith. This starts in operation the'stepping magnet which causes the yipers of the switches S1, 55,2, S3 and S4 to -rotate in the direction indilhen the wiper of the sending switch S1 moves onto the contact shown grounded, relay RD will be operated by current from battery B3 over the said contact to ground and contact 15 of the said relay will be opened and its contact 16 will be closed. By the opening of contact l5 relays RU and R7 will be deenergized provided relay R5 has opened its Contact which it will do provided the operator at A has ceased to operate the ringing keg' associated with the cord circuit of the plug P1. To guard against the contingency that the operator is still operating the ringing key lil, relay R8 is provided which vill be operated by the lclosing of contact 16 of relay R, and accordingly will open its contact l1 thereby releasing relays and RT.

.e rom the foregoing it will be seen that the arrangement thus far described provides for the application of relatively high frequency signaling current to a line for a deliniite interval of time and for guarding against possible variations of this interval which may result from careless operation.

ln order to effect the return of the wiper of the sending switch and also of the receiving switch (the wipers being Vconnected to the same shaft) to their normal inoperative into operation. The wipers of the rotary switch after reaching its grounded contact, will, on the nent impulse, be carried to the next succeeding contact, which contact upon the return switch S., is connected 'with the interrupter and also with the stepping magnet and its associated battery. Consequently current will iiow from battery B2 through the stepping magnet 3, conductor l?, conductor 18, through wiper of the switci S, and conductor 19, through the interrupter 2 to ground, thereby causing the said stepping magnet to move the wipers of the switches through one full cycle and to restore them linally to their normal positions. Relays R0 and RS are also restored to normal. y

Let. it be assumed that high frequency signaling current is being transmitted from the distant end of line L1 in. order to ,operate the' signal at A and that the cord circuit at A is not connected with the line circuit. Since it has been assumed also that the apparatus at the distant end of the line L, is similar to that shown in the ligure high frequency signaling current will be transmitted from the distant end of the line L1 by the operation of apparatus in a manner similar to that just described. This high frequency ringing current will beimpressed across the input circuit 5 bridge across the line L1 at the points el, il. Circuit 5 is connected with the input circuit 6 of the vacuum tube rectitier 7 and is tuned to transmit to the said input circuit current of 2000 cycles. Such tuned circuit is desirable because it will be seen that the low frequency signaling current is also impressed across the points 4, el whenever the operator at Aoperates her key K1, and it must be excluded from the receiving circuit. The high frequency signaling current will be impressed acrossthe vacuum tube rectiiier 7 and the resultant current will operate the relay R13 connected into the output side ofk the said rectiiier. This removes the ground from the normally operated circuit of the slow-release relay R12 thereby allowing its armature to fall back and to open the Contact of the said relay and likewise to close the contact 2l which in turn operates relay R11. By the operation of the latter relay a ground is putupon the proper contact of the receiving Iswitch S2 and likewise through the closingy of its right-hand contact, a circuit is estab-I positions, the switch S3 is brought CII tacts, is adapted to apply low frequency sigiialing current of approximately 20 1 cycles a second across the tip and ring sides of the switchboard end of the linewhich causes the operation of the relay R, bridged across the said conductor. Through. the operation of relay R1, R3 is likewise operated which causes the lighting of the line signal 1.

. Through the closing of the right-hand contact of relay R a circuit will be established from battery B3, winding ofrelaylr R through the contact of wiper of switch, SA, and the Contact of relay R10 and contact 2O of relay R1, to ground. Relay R12 remains deenergized as long as a ringing impulse isbeing received over the line L,

which, as has been previously described, depends upon the duration of time necessary for the wiper of the sending switch at the distant end of'line L1 to move over that 'pa-rt of the sector between its initial position and its grounded Contact. Consequently relay R12 will be operated shortly after the termination of the reception of such impulse over the line L1. rllhe release of its armature grounds through contact 20, the circuit of relay R15. `lVhen relay yR15 operates, a steady ground is put on the stepping magnet 3 which causes the latter to operate much more rapidly than would be the case were the said magnet connected to ground through an interrupting device such So, relay R15 in combination with switch S, will rapidly return the Wipers of the other switches to their normal positions.

lt will be seen from the foregoing that the arrangement in which this invention is embodied, provides for the control of the period of transmission of a highy frequency signaling current which is designed to avoid interference with other channels of transmission over the said line circuit and accordingly provides means for rendering this period of control independent of the period 'of time in which an operator may be yoperating the ringing key associated with lier cord circuit. The arrangement likewise provides means for controlling the period of `reception of the said signal and also means for restoring the wipers of the rotary switches to their normal position after the transmission or reception of signaling current,

Although this invention has been disclosed as embodied iny its specific form or 'arrangement of parts, it -is to be understood that the invention is not thus limited but is capabley of embodiment in other and different forms and arrangements without departing from the spirity and scope` of the appended claims. y c

"What is claimed is:

"l. ln a signalingsystemthe combination' y of a zline circuit, a sourceof high frequency current, la' source yof ylow frequency current,

means responsive to the said low frequency current to a'pplyythe said high yfrequencytoy the said 'line circuit, and means to 4disconf nectautomatically the said' high frequency current from the said line circuit'after a 'pre-determinedinterval of time'.

2. ln a. signaling systemr 'the combination of a line circuit, a source of high frequency current, a source of low frequency-current,

means for applying the said lowjfrequency current togthe said line circuit,^meaiis responsive to the said low frequency currenty yto control an application of the said highl frequency ycurrent yto the said line circuit and means to disconnect automaticallythe said high"frequency'current f romthe said j line circuit after a denite interval of time. f

3. In signaling` system the. combination of a linecircuit, a source" of high frequency current, a` source of low frequency current,

means controlled by the low frequencycur; y

rent to connect they said high frequencyk source to the said yline circuit, means for disconnecting they said high frequency source from the saidline circuit kafter a definite in-` terval of time, and vmeans to restore the said disconnecting means to its normal position after the said source of high frequency current has been disconnected from the said line circuit. i

f4. In a signaling system the combination y of a line circuit, a source of lovv frequency current, a source kof high frequency current, means responsive to the said low frequency current to apply the said high frequency current to the line circuit, meansto control the duration of the` period of connection of the said high yfrequency source with the said line circuit, and meansto render the duration of the said connection independent of the time during which the ylow frequency currentinay y be applied to the said responsive means.

5. In a signaling system the combination of a line circuit, a source of high frequency current adapted to be connected therewith,

a 'circuit connected with said line circuit` tuned to the frequency of the high frequencyy current, a thermionic rectifier, ya 'relay connected with the output side of the said rectifier, and responsive to the rectified current resulting from the impression of the said high frequency current upon the input' side of the said rectifier, and means controlled by' the said relay forl applying 10W frequency said rectier7 andresponsive to the rectified current` resulting from the impression of the Y said highrfequency current upon the input side oft-he said rectifier, and means responsive tov the operation .of the said relay for applying low frequency current to the line relay ofthe said line circuit and forliiuit-V ing the timeof application of the said., low

1 frequency current thereto. f

' 7. In a signaling system the combination of a linecircuit, va source ofhigh frequency` current adapted. tov be connected therewith, a circuit connectedwith saidline circuit tuned Lto the frequency ofthe high ifrequencyy current; a theimionic rectifier, a relay connected with the output side ofthe said rectifier1 and responsive to the rectifiedcurrent resulting from the impression ofthe said high'frequency current upon the input side of the said rectifier, a rotary switch, means .controlled by .thesaid relay for applyingto ground toa deiinitely fixed contact of the .said rotary switch and for controlling .the operation of the lWiper of the n said rotary switch, means responsive to the ,grounding of the vsaid wiper on the said Contact to cont-rol the application of the said low frequency current ,to the line relay of the said Aline circuit.

8. In a signaling` syste: i the combination with ay line circuit of cord circuits adapted, to be coiiiiecteclwitli eachend of. said line circuit7 sources of high frequency current adapted to be. nnpressed'upon said line cin cuit, a plurality of rotaryv switches adaptedto dotcrniiii-cd Lthc period of time for 'the transmission 4of said high vfrequency currents and switching means connected With said rotary switches to restore the said Yswitches/to their normal position at the eX- piratioii of the predetermined interval vof time. v y v 9. In a. signaling system, the combination of a transmissionlina a sourcelof Signaling current j of voice frequencyV and means re` sponsii/e to current of a different frequency-y for automatically controlling' the period of application-ofsaid signaling current to the said line. Y v

f In 'testimony whereof, i have signed my naine to this specificationy this V21st day of December 1920; v

JOHN F. TOOMEY. 

